High load-carrying turbo oils containing amine phosphate and thiosemicarbazide derivatives

Abstract

This invention relates to synthetic based turbo oils, preferably polyol ester-based turbo oils which exhibit exceptional load-carrying capacity by use of a synergistic combination of sulfur (S)-based and phosphorous (P)-based load additives. The S-containing additives of the present invention are thiosemicarbazide and its derivative, and the P-containing component is one or more amine phosphates. The turbo oil composition consisting of the dual P/S additives of the present invention achieves an excellent load-carrying capacity, which is better than that obtained when each additive was used alone at a treat rate higher than or comparable to the total combination additive treat rate, and the lower concentration requirement of the P-based additive allows the turbo oil composition to meet U.S. Navy MIL-L-23699 requirement on the Si seal compatibility.

What is claimed is: 
     
       1. A method for enhancing the load carrying capacity of a turbo oil comprising a base stock suitable for use as a turbo oil base stock by adding to said turbo oil base stock a minor amount of additives comprising a mixture of thiosemicarbazide, its derivatives and mixtures thereof and one or more amine phosphate(s), wherein the thiosemicabazide is used in an amount in the range of 100 to 1000 ppm and is represented by the structural formula: ##STR6## wherein R 5 , R 6 , R 7  and R 8  are the same or different and are hydrogen, C 1  -C 8  alkyl, C 2  -C 8  alklenyl, phenayl mono- and di- C 1  -C 4  alkyl phenyl, allyl, or ##STR7## wherein R 9  is C 1  -C 8  alkyl and wherein the amine phosphate is used in an amount in the range of 50 to 300 ppm and is of the formula: ##STR8## wherein R and R' are the same or different and are C 1  -C 12  linear or branched chain alkyl, R 1  and R 2  are H or C 1  -C 12  linear or branched chain alky; R 3  is C 4  to C 12  linear or branched chain alkyl or aryl-R 4  or R 4  -aryl wherein R 4  is H or C 1  -C 12  alkyl and aryl is C 6 .   
     
     
       2. The method of claim 1 wherein the base stock is a synthetic polyol ester. 
     
     
       3. The method of claim 2 wherein at least 2 of R 5 , R 6 , R 7  and R 8  are hydrogen. 
     
     
       4. The method of claim 2 wherein at least 3 of R 5 , R 6 , R 7  and R 8  are hydrogen. 
     
     
       5. The method of claim 1 wherein the amine phosphate and the thiosemicarbazide derivative are used in a weight ratio of 1:1 to 1:10. 
     
     
       6. The method of claim 1 wherein R and R' are C 1  to C 6  alkyl, and R 1  and R 2  are H or C 1  -C 4 , and R 3  is linear or branched C 8  -C 12  alkyl. 
     
     
       7. The method of claim 5 wherein the amine phosphate and the thiosemicarbazide, its derivative(s) or mixture thereof are used in a weight ratio of 1:1 to 1:5.